Buff Janna
Janna needs some QOL buffs.
Her Mana costs are really high for what you get out of her skills.
For you to get 80% slow from zephyr, at max level you would need 670 ap. No support would build this much AP they simply dont get enough gold, and have better things to spend gold on. With a ap ratio of 12% - 18% this would make the slow better with less ap and provide a better reason to actually use the active since using it slows her down, and makes her not able to pass through units.
Janna needs a buff to her aa range, Lux, and most adc have a base aa range of 550. Janna should have an aa range of 550 or 525.